1. Field of the Invention
The present invention relates to a technique of conveying a printing medium whose surface is coated with a special liquid.
2. Description of the Related Art
Some printing apparatus which prints on a printing medium includes a conveyance mechanism for conveying a printing medium. This conveyance mechanism generally includes a conveyance roller and a driven roller which presses the conveyance roller through a printing medium. As the conveyance roller rotates, the driven roller rotates in a direction opposite to that of the conveyance roller to convey a printing medium in the conveyance direction.
Some printing apparatus having an arrangement like that described above uses a printing medium whose surface is coated with a special liquid which quickens the coagulation of the pigment component contained in ink. This liquid is mixed with a solvent and has a higher viscosity than water. For this reason, a mixture of the liquid and paper dust tends to be generated on the surface of a printing medium. This mixture sometimes adheres to the driven roller at the time of the conveyance of a printing medium. The mixture adhering to the driven roller is pressed and hardened by the conveyance roller as the driven roller directly presses the conveyance roller after the conveyance of the printing medium. As a result, for example, a printing medium may be contaminated or the conveyance performance may deteriorate.
Japanese Patent Laid-Open No. 5-238580 discloses a cleaning apparatus for solving the above problem. This cleaning apparatus causes a cleaning sheet for cleaning the conveyance roller provided on a paper conveyance path to pass the conveyance roller. This removes foreign substances adhering to the conveyance roller.
The cleaning apparatus disclosed in Japanese Patent Laid-Open No. 5-238580 requires the cumbersome operation of preparing a cleaning sheet and setting it in the apparatus in place of a printing medium.